It has increasingly become recognized that electronic cigarette liquid (liquid nicotine, or “e-liquid”) can be harmful to children. Poison control centers have reported an increasing amount of calls resulting from children having exposed themselves, accidentally or otherwise, to e-cigarettes and liquid nicotine.
As a result, many governments have created rules or passed legislation mandating childproofing of electronic cigarettes. For example, some have required that electronic cigarettes or e-liquid be sold in child-resistant packaging, while others have required that electronic cigarettes or electronic cigarette cartridges themselves be childproofed. This has meant that many existing electronic cigarette designs, which do not feature an inherently childproof design, are inadequate to compete under new governing laws.
Some models of electronic cigarette do include child safety features. However, in those models, safety often comes at the expense of convenience. Making it difficult for a child to inadvertently access an electronic cigarette cartridge can often make it difficult for an adult to intentionally access the electronic cigarette cartridge. For example, if a user must partially disassemble an electronic cigarette before they are able to replace the cartridge, the cartridge will be well-protected from children, but the user will have to have access to tools (usually at least a screwdriver) and a workspace in order to insert a new cartridge and will likely not be able to insert a new cartridge right after purchasing it. Further, if the cartridge is secured so that it is not visible when in use, so that it does not provide a tempting target for a curious child, it can be difficult for the user to visually determine whether they have e-liquid material left in their cartridge (and if so, how much is left). This can cause the user to run out of e-liquid material at an inconvenient time, and can thus be undesirable.